Hydrocarbon fuel oil compositions



United States Patent Ofifice 2,699,385 Patented Jan. 11, 1955 HYDROCARBON FUEL OIL COMPOSITIONS No Drawing. Application April 19, 1951, Serial No. 221,936

17 Claims. (Cl. 52-.5)

This invention relates to improved fuels foruse in internal combustionengines of the diesel or compression ignitlon type, and for use in engines of the reactiontype,

such as rari'l-jet, turbo-jet engines and the like; more particularly, the invention concerns hydrocarbon fuel oil compositions having enhanced ignition characteristics.

In the manufacture of fuels for use in diesel type internal combustion enginesand reaction type engines, it has been found that many of the petroleum oil fractions whose boiling range, viscosity, and other physical characteristics render them potentially suitable for such uses have improper combustion .or ignition characteristics. In the case of diesel fuels, the unsatisfactory ignition qualities take the form of too great a time-lag between injection of the fuel into the cylinder and the spontaneous ignition thereof near the. end of the compression stroke, with consequent knocking, smoking, anduneven running of the engine. 'The extent of the time-lag or ignition delay of a diesel fuelis conveniently evaluated by a determination ofits so-called cetane number. In brief, the cetane number of a. fuel may be defined as the per cent by volume of cetane in a blend of cetane and alphamethylnaphthalene which has the same combustion characteristics as the fuel in question. A high cetane number indicates a low ignition delay period, and hence better performance as a diesel. fuel. In the case of. jet fuels, a similar problem is encountered in that a delay in ignition of the jet fuel upon injection. of the fuel into the engine prevents optimum performance of the reaction engine. Thus an increase in the cetane number of a fuel corresponds to a decrease in the ignition delay period, which is desirable in both diesel fuel and jet fuel.

In view of the relatively low cetane numbers of many t petroleum oil fractions which are otherwise suited for use as diesel fuels, it has been proposed to blend with such fractions additive materials which have the property of decreasing the ignition delay period, i. e. of increasing the cetane number of the fraction. improvement of the ignition characteristics of jet fuels by various additives has similarly been proposed.

Accordingly, it is an object of this invention to provide hydrocarbon fuel oil compositions wherein the combustion characteristics of the fuel are improved without adversely altering other desirable properties of the fuel oil.

More specifically, it is an object of our invention to improve the cetane number of diesel fuel compositions.

A further object of our invention is to provide improved jet fuel compositions which exhibit a decreased ignition delay period compared with unimproved jet fuels.

These and other objects are accomplished by the present invention wherein we provide improved fuel compositions comprising a major amount of a hydrocarbon fuel oil and a minor amount, sufiicient to increaseappreciably the burning rate of the fuel, of a compound having the following structural formula:

sisting of H, OI-Lalkenoxy, and alkoxy groups, the double .ther .allylation to produce allyl ethers bond in each alkenyl and alkenoxy group being at least one carbon atom removed from the alpha carbon atom thereof.

The alkenyl derivatives of this class, wherein the alkenyl group contains from 3 to 5 carbon atoms, are preferred, particularly where R1, R2, R3 are alkenyl'and R4 is alkenoxy. Illustrative of preferred alkenyl groups are allyl, butenyl, and 1,1-dirnethyla1lyl. Thus, both straight and branched chain groups are suitable.' It is also preferred to employ in the alkyl derivatives, alkyl groups containing from 1 to 18 carbon atoms. Methyl, ethyl, butyl, hexyl, octyl and decyl groups are illustrative. Both the alkenyl and alkyl groups may contain further substituent s which do not adversely affect the oil solubility of the compound or its ignition promoting characteristics.

To further illustrate the type of compounds falling within the scope of the above generic formula, the following specific examples of compounds are presented:

Mono-allyl phenol Diallyl phenol Mono-allyl resorcinol Diallyl hydroquinone Hydroquinone mono-butenyl ether Di--, l-dimethylallyl ether of catechol Butenyl ether of mono-allylphenol Mono-allyl ether of mono -butenyl resorcinol Diallyl ether of monobutenyl catechol Diallyl ether of diallyl catechol Mono-butyl ether of mono-butenyl hydroquinone Mono-butyl, mono-allyl ether of mono-allyl-resorcinol Mono-butyl, mono-allyl ether of di-allyl catechol Z-methyl, 4-allyl phenol Allyl ether of cre'sol 1, l-dimethylallyl ether of 2-butenyl-4-te1'tiary butyl phe- Ethyl ether of diallylphenol Mono-butyl ether of butenylhydroquinone Mono-methyl ether of di-l, 1-dimethylally1resorcinol Mono-butyl, mono-butenylether of allylcatechol Dibutyl ether of allylhydroquinone Dimethyl ether of .diallylcatechol Ethyl ether of 2-methyl-4al1ylphenol Mono-butyl ether of Z-methyl-6-allylhydro quinone Dimethyl ether of 4-allyl-6-.ethylcatechol The above compounds are prepared by methods wellknown in the art. For example, the alkenyl deriyatives can be prepared by alkylating a monoor di-hydroxy phenol with alkenyl chlorides under controlled conditions. Depending upon the. conditions employed, it is thus possible to obtain either nuclear substituted alkenylphenols, alkenylphenyl ethers, or both. By way of illustration, allyl phenols may be prepared by allylating phenols with allyl chloride to form the corresponding ethers, which may be employed as such; the ethers may also be rearranged to form the nuclear substituted allyl phenols. Alternatively, nuclear substituted allyl phenols may be prepared directly by allylation, followed by furof allyl phenols.

More specifically, allyl aryl ethers are usually prepared by refluxing a phenol with allyl bromide and anhydrous potassium carbonate for several hours in an acetone soample, involving tral and dried to constant weight. was 68.6 grams or 90.2% of theory based on the starting and allyl bromide in methanol solution, is more rapid than the procedure using acetone and potassium carbonate, and gives good results. Aqueous acetone also has been used as a reaction medium for the formation of allylethers of phenols by treatment of the phenol with sodium hydroxide and allyl halide. The following exthe preparation of the allyl ether of 4-octylphenol, is illustrative of such a procedure:

Example 1.To prepare 4-octylphenyl allyl ether, a mixture of 1.0 mol p-octylphenol, 1.0 mol sodium hydroxide, 300 ml. water, and 300 ml. acetone was made homogeneous by warming. Thereafter, 1.0 mol of allyl chloride was added slowly to the refluxing solution.

When about three-fourths of the total allyl chloride had been added, the reaction mixture became cloudy. Refluxing was continued for sixteen hours. The organic layer was separated off, dissolved in petroleum ether, washed with water, dried and distilled at reduced pressure from a Claisen flask.

The following cuts were taken:

Pressure, Temperature, Weight,

mm. 0. grams Cuts No. 1, 2, and 3 (representing a total yield of 88.3% theoretical yield of 4-octylphenyl allyl ether) were analyzed for iodine number and acetyl number with the following results:

By treatment of cuts No. 2 and 3 with Claisens alkali, phenolic contaminants of the ether were removed and the pure product analyzed as follows:

Iodine No. =105.4, Acetyl No.=

The simpler allyl aryl ethers can be rearranged by refluxing at atmospheric pressure until the boiling point becomes constant; since the boiling point of the product is higher than that of the ether, the boiling point rises until the reaction is complete.

Ethers of higher boiling point frequently undergo undesirable side reactions when refluxed at atmospheric pressure, and better yields may be obtained by refluxing at reduced pressure. .A similar result may be more conveniently obtained by using a solvent to act as diluent, such as dimethylaniline or diethylaniline. A non-oxidizing atmosphere such as nitrogen is recommended.

The reaction mixture is usually worked up by removing the basic solvent, if present, with dilute mineral acid, solution of the residue in petroleum ether, and extraction with aqueous alkali to separate the phenolic product from any neutral byproducts and unchanged ether. When the phenols are highly substituted, their acidity may be so greatly diminished that they are practically insoluble in aqueous alkali. Claisens alkali may be used then. Alkyl substituents in the aor 'y-position of the allyl group increase the rate of rearrangement. The preparation of 2-allyl-4-octylphenol by rearrangement of 4-octylphenyl allyl ether is illustrated by Example II.

Example II.-To 76.0 grams of 4-octylphenyl allyl ether (Iodine No. 104.5; Acetyl No. 51.5) were added 38.0 grams of diethylaniline. The solution was heated at 223-250 C. in a nitrogen atmosphere for about hours. The reaction mixture was dissolved in petroleum ether, then extracted with cold dilute sulfuric acid to remove diethylaniline. extracted several times with Claisens alkali. The alkaline extract was diluted with water, acidified with dilute hydrochloric acid and extracted with petroleum ether. The ether solution was Washed with distilled water until neu- The remaining ether solution was j Product yield obtained weight of 4-octylphenyl allyl ether. Iodine No.:; Acetyl No.=202.3. Theory for 2-allyl-4-octylphenol; Iodine No.=103, Acetyl No.=228. Further purification of this product was not attempted.

By suitable modification, the general procedure for the preparation of allyl ethers from phenols and their rearrangement to allyl phenols, as discussed supra, can be used for the preparation of the compounds listed hereinabove. As pointed out, nuclear substituted alkenyl phenols can also be prepared by direct C-alkenylation of the sodium salt of the phenol in benzene solution. In general, this method is not as effective for the preparation of allyl phenols as is the preparation of the allyl ether followed by rearrangement, because a mixture of products is obtained in C-alkenylation. .However, by employing the procedure outlined in U. S. Patent 2,459,835 to Monroe, direct nuclear allylation of dihydroxybenzenes occurs in good yield. Further allylation produces allyl ethers of allyl dihydroxybenzenes. As shown therein, the diallyldihydroxybenzene is formed by the nuclear alkenylation of the dihydroxybenzene with allyl halides, particularly allyl chloride. The pH of the aqueous reaction mixture should be maintained between 5 and 7 for maximum yield. Since the allylation reaction is exothermic, it is also necessary to maintain a low temperature, such as from 42 to 45 C., to avoid polymerization and secondary reactions. In addition, because hydrochloric acid is formed by the reaction, the allyl chloride is added to the dihydroxybenzene in a series of fractional portions and, prior to the addition of the allyl chloride, a base solution, such as sodium hydroxide, is introduced into the reaction mixture to neutralize the hydrochloric acid as formed. Furthermore, it is important that the dihydroxybenzene be dissolved in a buffer solution, such as sodium acid phosphate, the buffer acting to maintain the reaction solution pH between 5 and 7. Further allylation of the diallylcatechol thus prepared, with allyl chloride under similar conditions, except that the pH of the buffered system is held at 7 or above, will result in the formation of the diallyl ether of diallylcatechol.

The aforesaid procedure or obvious modifications thereof can be employed advantageously for the preparation of such compounds as the following:

Whether alkylation precedes alkenylation depends on \tilvhigh is more expedient for the particular preparation at The alkyl derivatives in turn are prepared by controlled alkylation with alkyl halides. They may also be prepared by alkylation with olefins in the presence of a condensation catalyst, such as concentrated sulfuric acid.

Suitable alkylating agents include ethylene, butene-l,

isobutylene, the amylenes, di-isobutylene, tri-isobutylene, and hexene.

A wide variety of diesel fuels and jet fuels are benefited by the class of compounds employed in accordance with our invention. hydrocarbon fuel oils is intended to include both types of fuels. Thus the hydrocarbon fuels of our invention include fuels boiling in-the range of 300 to 800 F. These fuels in turn may be prepared from gas oils, residual oils, recycle stocks, shale oils, coal tar oils, hydrogenated petroleum and coal tar oils, and various paraffinic, naphthenic or asphaltic base distillates, as well as synthetic hydrocarbon oils such as those produced by the Fischer-Tropsch synthesis. In accordance with cus- The designation of these fuels as tomary practice, the base fuel is usually blended from several types of stock to adapt it to a particulartypeof engine and specific operating conditions. As illustrative of suitable diesel fuels, the inspection data for several typical diesel fuels are set forth hereinafter in Table I.

TABLE I Typical diesel fuels Penn No. 2 Medium Heavy Gas Furnace Diesel 'Diesel Oil Oil Oil Oil As further illustrative of suitable fuels for use in accordance with our invention, the inspection data for a typical jet fuel is set forth in Table II. This .fuel is essentially kerosene boiling rangematerial. Jet engines, however, can utilize a considerable wider range of ma terials, both higher and lower boiling.

TABLE II Per cent residue 1.5 Per cent loss 0.0 Color, Saybolt +16 Acid heat, "F l1: Freezing point, "P 76 Accelerated Ginn test mg./ 100 ml 2.5 Glass dish Ginn mg./O ml- -a 0.2 Copper strip corrosion, 3 hr. at 212 F- Pass Flash point, TCC, "F 116 Vis. at 100 F. centistokes 1.48

The fuel oil compositions of our invention may be prepared simply by blending the additive into the fuel base in the desired proportions. Alternatively, in some in stances it may be more convenient to prepare a concentrate of the additive in the fuel base, and thereafter blend the concentrate with a further quantity of the same or a different fuel base to secure the desired composition.

In general, relatively minor amounts of the compounds set forth, such asfrom 0.01 to 10 per cent by weight of 'the fuel oil composition, are sufficient to increase appreciably the burning rate of the fuel.

Example lII.-The effectiveness of the herein-described class of compounds in improving the ignition characteristics of a typical diesel fuel is illustrated by the following data in Table III, obtained by determining the cetane number of an Eastern Venezuela straight-run fuel oil containing varying amounts of theallyl ether of 4-octylphenol prepared in accordance with Example I.

Example IV.-The results of similar tests conducted on an Eastern Venezuela straight-run fuel oil containing three per cent of the 2-allyl-4octylphenol prepared in accordance with Example II are set forth hereinafter in Table IV.

TABLE IV Oetane Cetane Fuel Composition Number Number Increase Eastern Venezuela straight-run fuel oil 45. 7 +13% (wt.) 2-allyl-4-oetylphenol 46. 7 1.0

Example V.The results of further tests on a typical diesel fuel are illustrated by the following data in Table V, obtained by determining the cetane number of a cracked diesel fuel containing varying amounts of diallylhydroquinone.

TABLE V Cetaue Cetane 1 Fuel Composition 7 Number Number Increase Light recycle FOO fuel oil distillate 29. 3 +1% (wt) diallylhydroquinone 29. 6 0.3 +21% (wt.) diallylhydroquinone 31.0 1. 7

Example VI.The results of similar tests conducted on a straight-run diesel fuel containing varying amounts of diallylcatechol are set forth hereinafter in Table VI:

TABLE VI Cetane Oetane Fuel Compositlon Number Number Increase Eastern Venezuela straight-run fuel oil 47. 7 +1.0% (wt.) of diallylcatechol 49. 1 1. 4 +30% (wt) of diallylcatcehol 49. 8 2.1

Example VII.Other tests conducted on a straight-run diesel fuel oil containing varying amounts of diallyl ether of diallyl catechol further indicate the eifectiveness of the ether derivatives as shown by the test data in Table VII:

It is readily seen that the diallylcatecholtested in'Example VI was more effective than the compounds tested in Examples III, IV and V. Moreover, the diallyl ether of diallylcatechol, tested in Example VII, was considerably more effective than any of the other compounds in the illustrative examples for improving the cetane number of the base fuel. The effect produced-by these compounds is surprising in view of the fact that cetane improvers are generally compounds rich in oxygen or in a highly oxidized condition, such as peroxides, po'lys ilphides, nitro and nitroso compounds, nitriles and the Thus it is evident that the employment of the class of compounds set forth in accordance with our invention results in hydrocarbon fuels characterized by increased burning rates or reduced ignition delay periods, such that important advantages may be obtained therefrom.

improvement of fuel oil ignition characteristics.

The improved fuel oil compositions provided by our invention may contain any of the agents commonly employed to enhance other properties of such fuels. For example, they may contain corrosion inhibitors, antioxidants, oiliness agents, detergents or dispersing agents, gum solvents, viscosity improvers, fuel oil stabilizers and the like. The class of compounds employed in accordance with our invention functions effectively in the presence of such agents.

Resort may be had to such modifications and variafrom the group consisting of fuel,,of a compound having the following structural formula:

R2 ORa wherein R1, R2 and Rs are selected from the group consisting of alkyl, alkenyl groups and H, at least one of R1, R2 and R3 being an alkenyl group, and R4 is selected H, OH, alkenoxy and alkoxy groups, the double bond in each alkenyl and alkenoxy group being at least one carbon atom removed from the alpha carbon atom thereof.

2. An improved fuel composition comprising a major amount of a hydrocarbon fuel oil and a minor amount, sufficient to decrease appreciably the ignition delay period 2f the fuel, of a compound having the following structural ormula:

wherein R1, R2 and Rs are selected from the group consisting of alkyl, alkenyl groups, and H, at least one of R1, R2 and R3 being an alkenyl group, and R1 is R2 OR:

wherein R1, and R2 and R3 are selected from the group consisting of alkyl, alkenyl groups, and H, at least one of R1, R2 and Ra being an alkenyl group, and R4 is selected from the group consisting of H, OH, alkcnoxy and alkoxy groups, said alkenyl and alkenoxy groups containing from 3 to 5 carbon atoms arranged such that the double bond'in each group is at least one carbon atom removed from the alpha carbon atom thereof, and said alkyl and alkoxy groups containing from 1 to 18 carbon atoms.

4. The composition of claim 1 wherein R1 and R2 are alkenyl, R3 is H, and R4 is OH.

5. The composition of claim 1 wherein R1, R2 and R3 are alkenyl, and R4 is alkenoxy.

6. An improved fuel composition comprising a major amount of a hydrocarbon fuel oil and a minor amount, sufiicient to increase appreciably the burning rate of the fuel, of a compound having the following structural formula:

R2 OR:

wherein R1 is alkyl, R2 is H, R3 is an alkenyl group, the double bond of which is at least one carbon atom removed from the alpha carbon atom of said group, and R4 is H.

7. An improved fuel composition comprising a major amount of a hydrocarbon fuel oil and a minor amount, sufficient to increase appreciably the burning rate of the fuel, of a compound having the following structural formu a:

wherein R1 is alkyl, R2 is an alkenyl group, the double bond of which is at least one carbon atom removed from the IaIlpha carbon atom of said group, and R3 and R4 are 8. An improved fuel composition comprising a major amount of a hydrocarbon fuel oil and a minor amount, sufficient to increase appreciably the burning rate of the fuel, of diallyl catechol.

-9. An improved fuel composition comprising a major amount of a hydrocarbon fuel oil and a minor amount, sufi'icient to increase appreciably the burning rate of the fuel, of diallyl hydroquinone.

10. An improved fuel composition comprising a major amount of a hydrocarbon fuel oil and a minor amount, sufficient to increase appreciably the burning rate of the fuel, of diallyl ether of diallyl catechol.

11. An improved fuel composition comprising a major amount of a hydrocarbon fuel oil and a minor amount, sufficient to increase appreciably the burning rate of the fuel, of the allyl ether of 4-octylphenol.

12. An improved fuel composition comprising a major amount of a hydrocarbon fuel oil and a minor amount, sutficient to increase appreciably the burning rate of the fuel, of 2-allyl-4-octylphenol.

13. The composition of claim 8 wherein the diallyl catechol is present in an amount of from about 0.01 to 10 per cent by weight of the composition.

14. The composition of claim 9 wherein the diallyl hydroquinone is present in an amount of from about 0.01 to 10 per cent by weight of the composition.

15. The composition of claim 10 wherein the diallyl ether of diallyl catechol is present in an amount of from about 0.01 to 10 per cent by Weight of the composition.

16. The composition of claim 11 wherein the allyl ether of 4-octylphenol is present in an amount of from about 0.01 to 10 per cent by weight of the composition.

17. The composition of claim 12 wherein the 2-allyl- 4-octylphenol is present in an amount of from about 0.01 to 10 per cent by weight of the composition.

References Cited in the file of this patent UNITED STATES PATENTS 1,987,228 Brunson Jan. 8, 1935 2,310,710 Rosenwald Feb. 9, 1943 2,410,847 Walters Nov. 12, 1946 2,637,161 Tschinkel May 5, 1953 

1. AN IMPROVED FUEL COMPOSITION COMPRISING A MAJOR AMOUNT OF A HYDROCARBON FUEL OIL AND A MINOR AMOUNT, SUFFICIENT TO INCREASE APPRECIABLY THE BURNING RATE OF THE FORMULA: 